Apparatus and method for aerating concrete



July 19, 1949. 2,476,551

I APPARATUS AND METHOD FOR AERATING CONCRETE J. G. A. JOJHNSON Filed April 24, 19 47 IN VEN TOR.

' ordinary concrete.

Patented July 19, 1949 UNITED STATES, PATENT OFFICE" APPARATUS AND METHOD FOR AERATING CONCRETE John Gunnar AmandusJohnson, New York, N. Y. Application April 24, 194171, Serial No, 743,659

3 Claims. (01.. 25-1) My invention relates to a new method and apparatus for treating concrete and other hydraulic cement mixtures after being poured in place for hardening.

' It is known that pores or cells within a concrete mass increase the insulating properties of concrete and decrease its weight. My proposed treatment produces a concrete which contains a multitude of air cells distributed in its mass and it holds therefore improved qualities against heat, cold and sound transmission as compared with- Due to its cellular structure it also weighs less than untreated concrete composed of the same kind of aggregates. The treatment to which I propose-to subject hydraulic [cement mixtures before setting is applicable to wall and slab construction poured in situ and to precast concrete and artificial stone products. My proposed method of treatment also offers effective means of attaining and controlling the degree of porosity desired for different requirements and different types of applications. a p

The object of my invention is therefore to provide a method an apparatus for creating air cells within a plastic concrete mass. I accomplish this result by injecting compressed air into the wet concrete, using an air pressure equal to or higher than the fluid pressure of the concrete at the depth at which the air injection is applied, while simultaneously controlling and varying the air pressure to proper operating compressions. The proportion of voids and total volume of treated concrete is controlled by varying the duration of air injection. My preferred apparatus is designed to create air pressure inside an enclosed chamber and is preferably made of rigid metal construction. This processing tool is adapted to be submerged in freshly poured concrete and is provided with perforations through which compressed air is injected into the concrete. The compressed air, which escapes through the perforations, may be dispersed thoughout the concrete mass by moving the tool horizontally or vertically or in a rotational manner during the processing operations. The volume of the mass is thus increased in proportion to the volume of the entrapped air. My preferred apparatus is also provided with an air outlet at the bottom of the air chamber leading to a pipe riser which connects to the atmosphere and a vent valve is provided at the top of the outlet pipe to control the outflow of the air. Thereby the operator has a ready means of regulating the air pressure in the chamber from a maximum pressure obtained with the outlet pipe closed to a minimum pressure with an open outlet. This arrangement permits wide variations in the compression of the air that is injected into the concrete and the operator can thus at all times quickly change the compression in the air chamber to an operating pressure corresponding to the submerged depth of the tool. Any mixing water that should accidentally enter the air chamber can readily be ejected by a free flow of air through the outlet pipe. I 1 Two forms which my invention may assume are exemplified in the following description and illustrated by way of example in the accompanying drawing, in which:

Figure lis a section through my preferred hand operated apparatus for treating deep concrete.

Figure -2 is a section through my preferred hand operated apparatus for treating slab concrete.

1 Figure 3 is a cross section on the lines 3-3 of Figures 1 and 2 on an enlarged scale showing the perforated part of the compression cham-' ber.

Figure 4 is a cross section on the lines 4-4 of Figures 1 and 2 on an enlarged scale through the upper part of the compression chamber.

' iInthe drawing where like reference numbers designate corresponding parts Figure 1 denotes my apparatus for treating deep concrete, which is preferably made of rigid metal tube construction. It comprises a flexible hose line I connected to an air compressor, not shown on the drawing, an entrance pipe 2 to the tubular body 6, which is provided with an air valve 3 and an opening 4 to the annular elongated compression chamber 5. The perforations 9 are provided in the lower portion of pipe 6 and inside the pipe a screen 10 is placed so as to prevent solid materials from entering the chamber through the perforations. An air pressure gauge 8 is preferably connected to the upper part of chamber 5. The outlet pipe l2 runs through the tubular body 6 with a restricted opening ll close to the bottom I of the chamber 5 and it is shown secured to the upper end of the tubular body 6 by the connection I3. An air vent valve I4 is placed at the upper end of the out let pipe [2 and a flexible exhaust hose 15 may be attached to pipe I! when desired.

In Figure 2, which illustrates my apparatus for treating slab concrete, l6 denotes a flexible hose line connected. to an air compressor, not shown on the drawing, I! an entrance pipe connected to the tubular handle 23, I8 is an air con.

trol valve and I9 is the entrance opening to the upper part of the compression chamber. The compression chamber is composed of three parts, the top part 20 inside the tubular handle 23, the annular elongated duct 2| and the two sym- 5 metrical lateral extentions 22. The compressed air enters part 20 of the compression chamber and flows through the duct 2| down into the lower horizontal extensionsa22, the WallsZSof which are provided with perforations 28' and a screen 10 29 is placed so as to prevent solid materials from entering the chamber 22. An air pressure gaugc"---' 21 is shown connected to the upper. endnof: the chamber. The branch pipes 3| are insertedjnq the lateral extensions 25 and reach close to the 15 ends 26 thereof so as to form a restrict-eddnlet W thereto. The branch pipes combine intoa. riser. pipe 32 which is provided with a connection 33 to the tubular handle 23. An air vent valvewfli is placed at the end of the pipe 32 to which an exhaust-hose 35-may be attached. a

The operation-of my preferred apparatu-s'isas follows: The air compressor; isstarted and the air. valve'on-the.entrance line is opened; The air, is compressed into the .air chamber and as the tool. islowered intothe concrete the air= escapes into.the;m-ix through-the small openings-inthe airchamber wall. The operator canreadily am just the compression to suit the known physical properties of the particular type of cement mix ture being treated. This is done by observing the: pressurefindicated on-the gaugeand. varying the, pressure by meanswof-the air outlet valve. It is a known fact that when-1ccm ipressed=airv is injectedinto water through a; small opening 3 the air will enter the .water: as a, .train'of bubbles. The same action takes place in my preferredatool when-:the air.pressurerissrightly adjusted; However, withoutdeparting. from :the scope; oflmy; invention, a more positive insurance for a bubbling a-irrinjection isprovided for inn a. tool inswhich a pulsating; air pressureis. created? I prefer; to cause-such a pulsatingjairinjeotiorr byg'either: a rotating valve element or a reciprocating piston action that intermittently; admits the air. into the tool chamber. The-tool: is; preferablyamoved back andforth. or up andsdown in the=plastic concrete and may be. provided with:a;rotatings.air chamber in order to :still .further; aid thee distri= bution ofrthe ainbubbl'es.

Itais to be .noted thatiI 'doznotlimitmy inventionto thevforms shownon' the'drawing-as itis' Having" now described my invention, What claim as' new therein and desire to secure by Letters Patent as follows:

* 1. The method to aerate a plastic concrete mix prior; to; its: setting characterized by injecting compressed air into the concrete mass by creating alternating low and high pressures, the low pressure substantially equal to or lower than the fluid pressure. in the concrete and the high pressure higher than the fluid pressure therein, While controlling-the pressure of the air that is injected into the concrete.

2.. The method. to aerate a plastic concrete mix priorato: its setting; characterized byv injecting compressed air into the: concretemass by; creatin alternating low and high pressuresathe: low pressiu-esubstantially equal to 'or' lowerzthanz the fiuidLpressure in the concreteand thehigh pressurerhigherr than the fluid pressure therein; while controlling the pressureof. the air-that is injected into the concrete and moving vthe;air'rinjection. to further the distribution of thecompres-sed: air; 3.. Anapparatus adapted to: injectlcompressed airinto a plastic concrete mass priortoits'setting comprising. in combination an airrchamber, a periora'ted Wall thereof: to contact: the concrete; a screen-erfor. the perforations; an outlet linefrom the bottom thereof, asrestricte'd'inletrtosaid line and an airroontrohoutle't' valve;

a J. GUNNAR'TALJOHNSON.

REFERENCES CITED The following; references are of record inthe file of thispatent:

UNITED STATES PATENTS Number Name Date" 13702.076 Ericson Feb. 12, 1929 2,215.223 Lytle Sept; 17.31940 212515687 Norton Aug. 5,- 1941 FOREIGN- PATEN IS Number Country Date L813 Great Britain July 31', 1856 

